TY - JOUR
T1 - Lowest triplet excited states of a novel heteroleptic iridium(III) complex and their role in the emission colour
AU - Costa, Rubén D.
AU - Viruela, Pedro M.
AU - Bolink, Henk J.
AU - Ortí, Enrique
N1 - Funding Information:
This work has been supported by the European Union (Heteromolmat, STRP 516982), the Spanish Ministry of Science and Innovation (MICINN; MAT2007-61584, CSD2007-00010, and CTQ2006-14987-C02-02), the Generalitat Valenciana and European FEDER funds. H.J.B. and R.D.C. acknowledge the support of the Program “Ramon y Cajal” and an FPU grant, respectively, of the MICINN.
PY - 2009/10/30
Y1 - 2009/10/30
N2 - The [Ir(ppy-F2)2Me4phen]+1 complex, where ppy-F2 is 2-(2′,4′-fluorophenyl)pyridine and Me4phen is 3,4,7,8-tetramethyl-1,10-phenanthroline, has been theoretically investigated by means of DFT calculations. The molecular and electronic properties calculated for [Ir(ppy-F2)2Me4phen]+1 are compared with those obtained for the simpler [Ir(ppy)(bpy)]+1 complex. The introduction of fluorine substituents in the ppy ligands and the use of phenanthroline instead of 2,2′-bipyridine as the diimine ligand increase the HOMO-LUMO energy gap and blue-shift the emission colour. The phenanthroline ligand causes the appearance of two nearly-degenerate LUMO orbitals of different symmetry in [Ir(ppy-F2)2Me4phen]+1 and determines that two almost isoenergetic doublet states are obtained for the reduced complex. Calculations predict three lowest-energy triplet excited states of different nature in an energy difference of only 0.10 eV. Emission from the 3LC π-π* state takes place at higher energies and accounts for the structured blue emission observed in solution. Emission from the lowest-energy 3MLCT state occurs in the green region and explains the structureless broad band observed in solid films.
AB - The [Ir(ppy-F2)2Me4phen]+1 complex, where ppy-F2 is 2-(2′,4′-fluorophenyl)pyridine and Me4phen is 3,4,7,8-tetramethyl-1,10-phenanthroline, has been theoretically investigated by means of DFT calculations. The molecular and electronic properties calculated for [Ir(ppy-F2)2Me4phen]+1 are compared with those obtained for the simpler [Ir(ppy)(bpy)]+1 complex. The introduction of fluorine substituents in the ppy ligands and the use of phenanthroline instead of 2,2′-bipyridine as the diimine ligand increase the HOMO-LUMO energy gap and blue-shift the emission colour. The phenanthroline ligand causes the appearance of two nearly-degenerate LUMO orbitals of different symmetry in [Ir(ppy-F2)2Me4phen]+1 and determines that two almost isoenergetic doublet states are obtained for the reduced complex. Calculations predict three lowest-energy triplet excited states of different nature in an energy difference of only 0.10 eV. Emission from the 3LC π-π* state takes place at higher energies and accounts for the structured blue emission observed in solution. Emission from the lowest-energy 3MLCT state occurs in the green region and explains the structureless broad band observed in solid films.
KW - Blue emission
KW - Emitting triplet states
KW - Heteroleptic iridium complexes
KW - Ligand-centered
KW - Metal-to-ligand charge transfer
UR - http://www.scopus.com/inward/record.url?scp=69949142519&partnerID=8YFLogxK
U2 - 10.1016/j.theochem.2009.02.031
DO - 10.1016/j.theochem.2009.02.031
M3 - Article
AN - SCOPUS:69949142519
SN - 0166-1280
VL - 912
SP - 21
EP - 26
JO - Journal of Molecular Structure: THEOCHEM
JF - Journal of Molecular Structure: THEOCHEM
IS - 1-3
ER -